The present invention relates to a driving device for a window wiper of a motor vehicle including a crank assembled of two crank parts hinged one to the other, one of the crank parts being fixedly connected to a reversible drive shaft and the other crank part being provided with a crank pin, a coupling rod hinged at one end thereof to the crank pin and at the other end thereof to a rocking lever which is linked to at least one wiper blade to impart thereto an oscillatory movement in a wiping field when the drive shaft turns in one direction; a control plate supported for rotation about the drive shaft and being provided with a guiding cam cooperating with a cam follower secured to the other cam part; a lock pawl pivotably mounted on the control blade to engage upon the reversal of the direction of rotation of the drive shaft, an indentation fixedly mounted on a frame of the motor vehicle; the crank being provided with another guiding cam cooperating with a cam follower on the lock pawl to displace the same into a locking position in which the control plate is locked and the other cam follower upon the reversal of the direction of rotation of the control shaft is rotated relative to the one crank part in such a manner that the crank pin is displaced outwardly away from the axis of rotation of the drive shaft and forces the wiper into a rest or parking position outside the wiping field.
A wiper driving device of this kind is known from the DE-OS No. 31 21 626 wherein the guiding cam has a radial component only and consequently the change in length of the articulated two part crank is initiated immediately after the reversal of the rotational direction of the driving shaft. As a result, the lock pawl is drawn near to its locking position before being actually situated opposite the corresponding locking indentation fixed to the frame of the vehicle. Therefore, such a prior art arrangement requires a high degree of manufacturing or installation precision and accordingly high manufacturing and installation costs result.